After-burner for an internal combustion engine

ABSTRACT

An after-burner for an internal combustion engine having a cylindrical recombustion chamber, an air inlet pipe connected to the cylindrical chamber for tangentially introducing air, a fuel inlet pipe connected to the cylindrical chamber at a port disposed in a first end of the cylindrical chamber, an ignition plug disposed in the first end for igniting the mixture of fuel and air, an exhaust gas inlet pipe connected to the cylindrical chamber for tangentially introducing exhaust gas from an internal combustion engine, and an outlet pipe connected to the cylindrical chamber at a port disposed in the second end of the cylindrical chamber coaxially to the cylindrical chamber for discharging gases from the cylindrical chamber.

Unite tates Inoue et a1.

atent 1 [ll] 3,8l3,879

[ June @1974 [73] Assignee: Toyota Jidosha Kogyo Kabushiki Kaisha, Toyota-cho, Toyota-shi, Japan [22] Filed: July 11, 1972 [21] Appl. No.: 270,837

[30] Foreign Application Priority Data 3,228,185 1/1966 Bergstrom 60/290 3,31 1,456 3/1967 Denny 23/277 C 3.484,!89 12/1969 Hardison.....

3,488,723 1/1970 Veazie 60/282 Primary Examiner-Douglas l-lart Attorney, Agent, or Firm-Stevens, Davis, Miller &

Mosher 5 '7 ABSTRACT An after-burner for an internal combustion engine having a cylindrical recombustion chamber, an air inlet pipe connected to the cylindrical chamber for tangentially introducing air, a fuel inlet pipe connected to the cylindrical chamber at a port disposed in a first end of the cylindrical chamber, an ignition plug disposed in the first end for igniting the mixture of fuel and air, an exhaust gas inlet pipe connected to the cylindrical chamber for tangentially introducing exhaust gas from an internal combustion engine, and an outlet pipe connected to the cylindrical chamber at a port disposed in the second end of the cylindrical chamber coaxially to the cylindrical chamber for discharging gases from the cylindrical chamber.

7 Claims, 10 Drawing Figures l/Il/Il/II/IIII/II/I/II/III PATENTEUJUH my I 38111879 SHEU 1 BF 2 PRIOR ART 2 m 9 f8 FlG,'2 FlG'a.

AFTER-BURNER FOR AN INTERNAL COMBUSTION ENGINE BACKGROUND OF THE INVENTION This invention is directed to an after-burner for purifying exhaust gases from an internal combustion engine. More particularly, it relates to an after-burner in which combustible components in the exhaust gases are ignited and combusted by a rotary, annular flame helically defining an elongated hollow cylinder.

A conventional after-burner, in general, uses a spark produced by an ignition plug for ignition and combustion of unburned and incompletely burned components in the exhaust gases from an internal combustion engine. By means of an ignition plug, however, the thermal energy of the spark is often not sufficiently high to ignite the exhaust gases once, and the spark cannot be produced continuously, thus causing misfires or blowouts of the flame. Accordingly, it is diflicult to burn completely the unburned and incompletely burned components. In order to ensure combustion of the exhaust gases, it is desirabie to produce sparks repeatedly.

It is well known that a vortex type combustion chamber produces a stable rotary columnar flame which has a high thermal energy. For example, such a rotary columnar flame is produced in the devices described in U. S. Pat. application (Ser. No. 1 16,028; filed on Feb. 17, 1971) which comprises a vortex combustion chamber for producing a rotary columnar flame and a separate recombustion chamber connected to the vortex combustion chamber for recombusting exhaust gases from an internal combustion engine. The prior after-burner is explained in more detail in conjunction with the drawings in this application.

Referring to FIGS. 1-3, an after-burner comprises a vortex combustion chamber 1, and a separate exhaust gas combustion chamber 8. Vortex chamber ii further comprises an air inlet pipe 2. connected thereto for tangentially introducing air therein, and a fuel inlet pipe 3 connected thereto at a port disposed in one end thereof. An evaporator is disposed in the same end,

along with an ignition plug 5 for igniting a mixture of 5 fuel and air. The separate exhaust gas combustion chamber comprises an exhaust gas inlet pipe 9 connected thereto for introducing the exhaust gas from the internal combustion engine, and a combustion gas outlet pipe 10 radially connected for discharging gases. Chambers 1 and 8 are separated by a partition wall 6 and connected to each other through an inlet port 7 disposed in partition wall 6 along the axis of both chambers. Fuel supplied into vortex combustion chamber through fuel inlet pipe 3 is converted into the gaseous state by evaporator 4 and mixed with air tengentially introduced into vortex combustion chamber 1 through air inlet pipe 2. The mixture of fuel and air is ignited by a spark produced by ignition plug 5, and burns so that the flame produced moves in rotating columnar form around the axis of vortex combustion chamber 1. Accordingly, a rotary annular flame is produced and it is injected into exhaust gas combustion chamber 8 through inlet port 7. Combustible components of the exhaust gases, such as carbon monoxide, unburned hydro-carbons and the like, are instantly ignited and burned by the rotary annular flame, and burned gases are discharged from combustion chamber 8 through outlet pipe 10. I

However, this prior after-burner has some disadvantages. Although the rotary annular flame is stable in vortex combustion chamber 1, as soon as it enters in exhaust gas combustion chamber 8, it diverges in a form like a trumpet. Accordingly, flame density (a density of burning gas) decreases, at the same time the rotary moment of the rotary annular flame becomes very small. When the exhaust gases from the engine are introduced in combustion chamber 8 in jet-like form, even tangentially, the flame is blown out quite readily. Thus, in order to keep a stable flame in exhaust gas combustion chamber 8, some sort of flame stabilizing equipment is needed. Besides, the flame renders shortening of the life of the inner surface of the exhaust gas combustion chamber 8 because the flame diverges in exhaust gas combustion chamber 8 and directly erodes the inner surfaces.

SUMMARY OF THE ENVENTION The present invitation obviates the aforementioned disadvantages of the prior art and improves the performance significantly. Specially, it can keep a flame stable without any sort of flame stabilizing equipment and the temperature of a wall of the after-burner low.

An object of this invention is to provide an afterburner for an internal combustion engine which will readily and surely ignite unburned components and incompletely burned products in exhaust gases, obtain a stable flame therein and thereby remarkably purify the exhaust gases.

Another object of the invention is to provide an afterburner which has a longer life than the prior art afterburners.

Further objects, as well as other features and advantages of the invention, will be shown in conjunction with the detailed description of the invention which comprises a unitary cylindrical recombustion chamber. An air inlet pipe for tangentially introducing air into the recombustion chamber, a fuel supply pipe, and ignition plug disposed in one end of the recombustion chamber, a tangential exhaust gas inlet pipe, and an exhaust outlet pipe disposed in the center of the other end of the unitary recombustion chamber.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a schematic sectional view of one embodiment of a prior art after-burner;

FIG. 2 is a left side view of the after-burner in FIG.

FIG. 3 is a sectional view taken along the line A-A of FIG. 1;

FIG. 4 is a schematic sectional view of an afterburner for an internal combustion engine comprising one embodiment of the present invention;

FIG. 5 is a left end view of the after-burner in FIG.

FIG. 6 is a sectional view taken along the line B-B of FIG. 4;

FIG. 7 is a schematic sectional view of an afterburner for an internal combustion engine comprising another embodiment of the invention;

FIG. 8 is a left end of the after-burner in FIG. 7;

FIG. 9 is a schematic sectional view of an afterburner for an internal combustion engine comprising another embodiment of the invention; and

FIG. 10 is a left end view of the after-burner in FIG. 9.

DETAILED DESCRIPTION OF THE INVENTION FIGS. 4-6 show an embodiment of this invention, wherein the same reference numbers indicate substantially the same elements as in FIGS. 1-3. A recombustion chamber Ili comprises exhaust inlet pipe 9 for tangentially introducing exhaust gases from an internal combustion engine. An outlet pipe it) is connected to recombustion chamber if at an outlet port H which is coaxially disposed in the center of the exit end of chamber M. The evaporator 4 is comprised of a porous refractory substance.

The operation of this invention is explained below:

As soon as the engine is started, fuel is supplied to recombustion chamber ill through fuel inlet pipe 3 and evaporator 4 by a fuel pump (not shown) which is operated by the engine. The fuel is mixed with air tangentially introduced through air inlet pipe 2, and the mixture of fuel and air is ignited by a spark produced by ignition plug 5. Once fuel is ignited, evaporator 4! is heated by the flame created in recombustion chamber 1!, and fuel is thereby immediately evaporated while it flows through evaporator 41, for facilitating ignition of the mixture of fuel and air. Then outlet port 113 is disposed coaxially in the center of the other end of recombustion chamber Ill, and air is introduced tangentially, so that a forced vortex domain is created around the axis of recombustion chamber El and a free vortex domain is created around the forced vortex domain. Both vortex domains are very stable. A combustion flame is held along a boundary surface between the forced vortex domain and the free vortex domain. A stable rotary annular flame is thereby produced in recombustion chamber II. Meanwhile, through exhaust inlet pipe 9, exhaust gases from the engine are introduced tangentially to recombustion chamber II. This promotes a rotary motion of the forces vortex and the free vortex and makes the rotary columnar flame stronger and more stable. At the same time, exhaust gases from the engine are mixed with the mixture in combustion chamber 111, and harmful combustible components in the exhaust gases are burned before being exhausted from recombustion chamber ll. According to this invention, the rotary moment of the rotary annular flame is preserved throughout recombustion chamber it, and promoted by tangentially introducing the exhaust gases. Accordingly, the rotary columnar flame is steadily held. Also, because of the vertexes, gases introduced in recombustion chamber ll can stay therein for a long time. Consequently, unburned components and incompletely combusted products in the exhaust gases are completely burned in recombustion chamber 11 because of the action of the strong stable rotary columnar flame as an ignition source throughout a sufficient period of time. Besides, since the rotary columnar flame is enveloped by the exhaust gas, the flame does not touch the inner walls of recombustion chamber 11. As a result, recombustion chamber I1 is protected from severe erosion.

In FIGS. 7 and 8, which show another embodiment of this invention, the same reference numbers indicate substantially the same elements as in FIGS. 1- 6, and

the structure is similar to the first embodiment shown in FIGS. 4-6, except that this embodiment has another chamber connected to recombustion chamber i1 through outlet port 13, and outlet pipe 10 is radially connected to another chamber. According to this embodiment, an exhaust pipe (not shown) may be connected radially with recombustion chamber It.

In FIGS. 9 and 10, which show another embodiment of this invention, the same reference numbers indicate substantially the same elements as shown in FIGS. 7 and 8, and the structure is similar to the second embodiment shown in H08. 7 and 8, except that this embodiment has four exhaust gas inlet pipes 9 which may be connected to the port of each cylinder of an engine (not shown).

It will be understood from the foregoing description that a feature of this invention based on a stable rotary columnar flame, which has a large heat energy, is to provide an after-burner for an internal combustion engine which may easily ignite exhaust gases, even if there are large variances of the input quantity of the exhaust gases.

Another feature of this invention is to provide an after-burner for an internal combustion engine which increases the chances for exhaust gases from an engine to contact a flame as a heat source and then to burn completely uncombusted components and incompletely combusted products in the exhaust gases.

Another feature of this invention is to provide an after-burner for an internal combustion engine which warms up an exhaust system as a whole.

A still further feature of this invention is to provide an after-burner for an internal combustion engine which minimizes the temperature of the outer shells of the after-burner.

From the aforementioned, the construction of the device will be readily understood, and further explanation is believed unnecessary. However, since numerous modifications and changes will readily occur to those skilled in this art, it is not desired to limit the invention to the exact construction shown and described; accordingly, applicants claim all suitable modifications and equivalents falling within the scope of the appended claims.

What is claimed is:

1. An after-burner for an internal combustion engine, comprising:

a unitary cylindrical recombustion chamber;

a first air inlet pipe connected to said chamber for tengentially introducing air;

means disposed in one end of said chamber for introducing fuel;

means disposed in said one end of fuel and air; and

a second gas inlet pipe connected to said chamber for tangentially introducing an exhaust gas from an engine into said chamber;

the other end of said chamber having a circular outlet port located coaxially with the axis of said chamber.

2. The after-burner of claim 1, wherein a sidewall of said chamber includes an air inlet port at which said air inlet pipe is connected to said chamber.

3. The after-burner of claim 1, wherein said fuel introducing means comprises a fuel inlet pipe connected to said chamber, and

for igniting a mixture means disposed in said one end for evaporating fuel.

6. The after-burner of claim 1, further comprising a chamber connected thereto through said outlet port, said latter chamber having an outlet pipe radially connected to said latter chamber. 7. The after-burner of claim 6, wherein said after" burner further comprises plural exhaust gas inlet pipes connected to said recombustion chamber. 

1. An after-burner for an internal combustion engine, comprising: a unitary cylindrical recombustion chamber; a first air inlet pipe connected to said chamber for tengentially introducing air; means disposed in one end of said chamber for introducing fuel; means disposed in said one end for igniting a mixture of fuel and air; and a second gas inlet pipe connected to said chamber for tangentially introducing an exhaust gas from an engine into said chamber; the other end of said chamber having a circular outlet port located coaxially with the axis of said chamber.
 2. The after-burner of claim 1, wherein a sidewall of said chamber includes an air inlet port at which said air inlet pipe is connected to said chamber.
 3. The after-burner of claim 1, wherein said fuel introducing means comprises a fuel inlet pipe connected to said chamber, and means disposed in said one end for evaporating fuel.
 4. The after-burner of claim 3, wherein said one end includes a fuel inlet port at which said fuel inlet pipe is connected to said chamber, and said fuel evaporating means comprises a porous material which is disposed over said fuel inlet port.
 5. The after-burner of claim 1, wherein said igniting means comprises an ignition plug.
 6. The after-burner of claim 1, further comprising a chamber connected thereto through said outlet port, said latter chamber having an outlet pipe radially connected to said latter chamber.
 7. The after-burner of claim 6, wherein said after-burner further comprises plural exhaust gas inlet pipes connected to said recombustion chamber. 